The present invention relates to underground vaults for storing batteries and, more specifically, to the storage of batteries used by electrical devices such as uninterruptible power supplies distributed throughout a communications system.
Electrical devices are often stored in remote locations and employ batteries for primary or standby power. For example, uninterruptible power supply (UPS) systems are often distributed throughout communications systems to provide power to active components of such systems in the event of utility power failure. Many such UPS systems are connected to batteries that provided power that allows the communication system to operate for a short period of time until utility power is recovered or another source of power can be started.
The present invention is of particular relevance when used in connection with UPS systems distributed throughout a communications system, and that application will be described in detail herein. However, the present application may have broader application to other electrical devices, so the scope of the present invention shall be determined by the claims appended hereto and not the following detailed description.
The batteries used by such UPS systems are may be stored in cabinets attached to utility poles or in above-ground cabinets but are often stored in underground vaults. Underground vaults are commonly a concrete, fiberglass, and/or plastic structure that is buried adjacent to the UPS system. A cable is run from the batteries in the vault to the UPS system to allow the UPS system to generate a standby AC power signal from the DC battery power signal.
Underground storage of UPS batteries is often preferable to above surface cabinets, pole mounted cabinets, and the like for a variety of reasons. In particular, underground vaults: do not require above ground cabinets and thus have less aesthetic impact on the surrounding environment; maintain the batteries at cooler temperatures and thus prolong battery life, which can increase reliability of the UPS system; are less susceptible to damage from vandalism and vehicle accidents; are easier to access for maintenance staff; and are relatively cost-effective to install and upgrade with fewer siting limitations.
A primary problem with underground battery vaults is that a high water table, poor drainage, and the like can flood the battery compartment defined by the vault. A flooded battery compartment can result in short circuiting of the battery terminals and accelerated corrosion of the terminals and related hardware. In addition, such ground water can deposit mud, silt, and other debris on the battery terminals and related hardware that remains after the flood recedes and can interfere with reliability, maintenance, and proper operation of the batteries.
Another problem is that the batteries themselves can fail in a number of ways that might release battery chemicals into the environment.
The need thus exists for systems and methods that protect and contain batteries stored in underground vaults.
Bell jar systems are often used to protect batteries in underground vaults from flooding. A bell jar system attempts to form a chamber at the top of a battery that traps air over the battery terminals and related hardware during flood conditions. Under some conditions, the trapped air will prevent the terminals and related hardware from becoming immersed in water even if the vault is completely flooded.
However, in many conditions bell jar systems fail to protect the battery terminals and related hardware. Voids, cracks, and holes in the bell jar structure can prevent the trapping of air, allowing the battery terminals and related hardware to be flooded. Even if the bell jar structure properly traps air around the upper portion of the battery, a number of problems can arise.
First, the trapped air will be relatively moist, which results in condensation on the battery terminals and related hardware. This condensation can establish a leakage path that will reduce the effectiveness of the batteries as part of the UPS system electrical circuit and may result in accelerated corrosion because of dissimilar metals used to manufacture the terminals and related hardware.
Second, not only will air be trapped, but hydrogen vented from the batteries may also be trapped. This build-up of hydrogen is undesirable for a number of reasons.
The need thus exists for improved systems and methods for protecting and containing batteries stored in underground vaults.
The present invention is a vault system for batteries that supply a battery power signal to an electronic device. The vault system preferably comprises an enclosure assembly, a control enclosure, at least one terminal set, and one or more lead pairs. The enclosure assembly contains the batteries. The control enclosure assembly is arranged within the enclosure assembly. The at least one terminal set is arranged within the control enclosure. At least one lead pair is associated with each battery and each lead pair is connected at one end across terminals of the battery associated therewith and at another end to the terminal set. Power cables extend from the control enclosure to the electronic device. The terminal set interconnects the lead pairs and the power cables such that the battery power signal is generated by the batteries connected to the at least one lead pair and present across the power cables. Other configurations are possible within the broader scope of the present invention.